tag:theconversation.com,2011:/ca/topics/hawk-eye-8441/articlesHawk-Eye – The Conversation2017-01-25T00:01:42Ztag:theconversation.com,2011:article/709422017-01-25T00:01:42Z2017-01-25T00:01:42ZOur psychological biases mean order matters when we judge items in sequence<figure><img src="https://images.theconversation.com/files/206289/original/file-20180213-44660-5628to.jpg?ixlib=rb-1.1.0&rect=84%2C62%2C3510%2C2034&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Does gold go to the best snowboarders or the ones with the best place in the order?</span> <span class="attribution"><a class="source" href="http://www.apimages.com/metadata/Index/Pyeongchang-Olympics-Medals-Ceremony-Snowboard-Women/98cf79e3e4c440cea18764a524084943/4/0">AP Photo/Morry Gash</a></span></figcaption></figure><p>We often need to make decisions about sequences of things or people rather than just a single item in isolation. For instance, in an everyday setting, we might choose which smartphone to buy after trying out several. There are also more high-stakes situations, of course, like when Olympic athletes compete in a set order as they try to win the gold.</p>
<p>Ideally, it wouldn’t matter when in the sequence you came across the best item or the most outstanding performance, and we certainly hope that scores will be determined in an unbiased way. If they weren’t, competitors would (rightly) complain about how unfair the process was.</p>
<p>But it turns out that people show many biases when performing these sorts of judgment tasks. Our subjective evaluations are influenced by context – that is, the other items to be judged have an effect, even though they probably shouldn’t. For example, people rate faces presented <a href="http://doi.org/10.1177/0956797613497969">in a group photo as more attractive</a> than when each is rated individually. <a href="http://rsos.royalsocietypublishing.org/lookup/doi/10.1098/rsos.160812">My latest study</a> adds to the body of psychology research showing that context also includes previously seen faces, athletes and so on.</p>
<h2>Where in the order?</h2>
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<a href="https://images.theconversation.com/files/154258/original/image-20170125-23845-yqgwbn.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/154258/original/image-20170125-23845-yqgwbn.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/154258/original/image-20170125-23845-yqgwbn.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=775&fit=crop&dpr=1 600w, https://images.theconversation.com/files/154258/original/image-20170125-23845-yqgwbn.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=775&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/154258/original/image-20170125-23845-yqgwbn.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=775&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/154258/original/image-20170125-23845-yqgwbn.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=974&fit=crop&dpr=1 754w, https://images.theconversation.com/files/154258/original/image-20170125-23845-yqgwbn.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=974&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/154258/original/image-20170125-23845-yqgwbn.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=974&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
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<span class="caption">Aim to be first or last when auditioning.</span>
<span class="attribution"><a class="source" href="http://www.apimages.com/metadata/Index/TV-American-Idol-Auditions/f1cc8e1a4b4e44249976c2677b419433/1/0">AP Photo/Chris Park</a></span>
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<p>People are affected by where an item appears in a sequence. We know that the first and last items are <a href="http://dx.doi.org/10.1016/S0022-5371(66)80044-0">remembered best</a>. They’re also <a href="http://dx.doi.org/10.1016/j.jebo.2009.08.012">judged more positively</a> during competitions. So if you plan to perform in the “Idol” television series, for instance, you’d be wise to sing at the start or end of the lineup if you can nudge your way there.</p>
<p>How we judge a performance is also affected by the score we just gave. This is because the most immediate (recent) events are used as points of reference – such information is readily accessible, increasing its influence on current decision-making.</p>
<p>Usually, this takes the form of what psychologists call an <a href="https://en.wikipedia.org/wiki/Assimilation_and_contrast_effects">assimilation effect</a>: If the previous person (or thing) receives a high score, it increases our evaluation of the current person. Conversely, when the previous performance is scored poorly, it decreases the current person’s evaluation.</p>
<p>This pattern seems to be the default for people when presented with sequences. Researchers have identified this type of effect in a variety of situations, including the scoring of <a href="http://dx.doi.org/10.1037/1076-898X.12.3.166">Olympic gymnasts</a>, estimates of <a href="http://journal.sjdm.org/81104/jdm81104.html">item prices</a>, ratings of <a href="http://dx.doi.org/10.1177/0013164410387344">students’ essays</a> and how we judge <a href="http://dx.doi.org/10.1371/journal.pone.0082226">attractiveness</a>.</p>
<p>On the other hand, sometimes we see the opposite pattern – what psychologists call a <a href="https://en.wikipedia.org/wiki/Assimilation_and_contrast_effects">contrast effect</a>. In this case, giving a low score to the previous performance will increase the current person’s evaluation. And similarly, giving a high score decreases the rating of the next.</p>
<p>In this case, it seems like your best bet is to compete right after someone who received a low score because they’ll make you look better. Evidence of this type of pattern has been found in <a href="http://dx.doi.org/10.1162/REST_a_00416">speed-dating judgments</a>. In my recent research, <a href="http://rsos.royalsocietypublishing.org/lookup/doi/10.1098/rsos.160812">we saw the same pattern in Olympic synchronized diving scores</a>. When divers competed right after lower-scoring dives, this boosted their scores, but following a great dive led to athletes receiving lower ratings from the judges. Statistically, I found medium effect sizes in most cases.</p>
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<a href="https://images.theconversation.com/files/152303/original/image-20170110-29003-1r1ldce.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/152303/original/image-20170110-29003-1r1ldce.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/152303/original/image-20170110-29003-1r1ldce.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=420&fit=crop&dpr=1 600w, https://images.theconversation.com/files/152303/original/image-20170110-29003-1r1ldce.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=420&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/152303/original/image-20170110-29003-1r1ldce.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=420&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/152303/original/image-20170110-29003-1r1ldce.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=528&fit=crop&dpr=1 754w, https://images.theconversation.com/files/152303/original/image-20170110-29003-1r1ldce.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=528&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/152303/original/image-20170110-29003-1r1ldce.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=528&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
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<span class="caption">Women’s synchronized diving scores are influenced by the previous dive.</span>
<span class="attribution"><a class="source" href="https://commons.wikimedia.org/wiki/File:Women_Synchronized_10_metre_platform.jpg">松雪</a>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span>
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<h2>So will you get a bump or take a hit?</h2>
<p>Researchers are still trying to understand when our judgments will be assimilated and when they will be contrasted with the previous score.</p>
<p>Some evidence suggests <a href="http://dx.doi.org/10.1037/0033-295X.110.3.472">similarity is the key</a>. If the current and previous items are similar enough, judges will show assimilation and rate the subsequent item closer to the previous one. But if they are seen to be sufficiently different, a contrast effect will take place and the following item’s rating will be pushed further away. For instance, by altering how similar two consecutive gymnasts appeared (telling participants that they had the same or different nationalities), researchers were able to <a href="http://dx.doi.org/10.1037/1076-898X.12.3.166">produce either assimilation or contrast effects</a> in participants’ ratings.</p>
<p>The idea is that initial similarities lead people to search for more of them – these might include similar appearance, age group and so on – causing assimilation. However, when there are obvious differences or judges are already looking for differences, that’s when you see contrast effects.</p>
<p>With the synchronized divers, for instance, I hypothesize that judges are trained to look for the tiniest differences between diving partners (who aim to give identical dives) since these will lead to deductions in their scores. This focus on differences might then generalize to searching for differences from one pair to the next, producing an overall contrast effect for the sequence.</p>
<p><a href="http://dx.doi.org/10.1016/j.visres.2005.05.014">Timing may also play a role</a>. If presentations are very short (fractions of a second, which can be produced in the lab), this may increase the likelihood of assimilation. For longer viewing times, which are more common in natural settings, we may be more likely to see contrast effects. Evidence also suggests that any type of previous-item influences may decrease or vanish altogether when the <a href="http://dx.doi.org/10.1177/0013164410387344">time between items</a> in the sequence is longer.</p>
<h2>Removing biases</h2>
<p>Perhaps the best way to prevent these types of biases from affecting competition outcomes is to remove the so-called human element. <a href="http://dx.doi.org/10.1109/ICME.2008.4607580">Computer analysis of synchronized dives</a>, for example, might eventually provide objective measures of performance that could be combined with, or even replace, human judging.</p>
<p>Automatic systems like <a href="https://en.wikipedia.org/wiki/Hawk-Eye">Hawk-Eye</a> are already being used in tennis, cricket and several other sports as an impartial second opinion. By visually tracking the ball’s movement, these systems can create a 3D representation of its trajectory. Perhaps other types of decisions in competition may one day also be aided by an artificial judge.</p>
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<a href="https://images.theconversation.com/files/152319/original/image-20170110-29000-9npw58.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/152319/original/image-20170110-29000-9npw58.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/152319/original/image-20170110-29000-9npw58.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=803&fit=crop&dpr=1 600w, https://images.theconversation.com/files/152319/original/image-20170110-29000-9npw58.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=803&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/152319/original/image-20170110-29000-9npw58.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=803&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/152319/original/image-20170110-29000-9npw58.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=1009&fit=crop&dpr=1 754w, https://images.theconversation.com/files/152319/original/image-20170110-29000-9npw58.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=1009&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/152319/original/image-20170110-29000-9npw58.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=1009&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
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<span class="caption">Systems like Hawk-Eye keep watch at sporting events to give unbiased judgments.</span>
<span class="attribution"><a class="source" href="https://commons.wikimedia.org/wiki/File:Kremlin_Cup_2012_-_Hawk-Eye_cam.JPG">JukoFF</a>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span>
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<p>Since technology is not yet able to replace human judgments, there may be certain steps we can take to make competitions as fair as possible. First, randomizing the order of competitors will prevent any particular athlete from having a greater chance of appearing in an advantageous position in the sequence (although this won’t remove the biases mentioned). Second, increasing the time between performances as much as possible (subject to the limits of TV broadcasting, human concentration and so on) should decrease some of these biases. Third, I would predict that improving conditions for judges – for instance, giving them more time or allowing them to view the slow-motion replay – could also lead to a decrease in comparisons with previous performances.</p>
<p>To date, there has been little investigation into how these types of biases might be affecting real-world behaviors and competitions. Realizing that athletes could win or lose Olympic medals based upon where in a sequence they compete is both surprising and worrying. With more research into these biases, we can figure out how to prevent them from influencing important outcomes like who goes home with the gold.</p><img src="https://counter.theconversation.com/content/70942/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Robin Kramer does not work for, consult, own shares in or receive funding from any company or organization that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>Whether it’s items in a shop, potential speed-dating matches or athletes competing one after another, the order in which they’re presented affects our judgments.Robin Kramer, Lecturer in the School of Psychology, University of LincolnLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/660002016-09-26T13:17:57Z2016-09-26T13:17:57ZVideo refereeing could be a major own goal for football – here’s why<p>Ajax’s 5-0 cup victory against fellow Dutch premier division side Willem II on September 21 <a href="https://www.theguardian.com/football/2016/sep/22/anouar-kali-first-player-sent-off-video-assistant-referee">saw a first</a> in football: the official world debut for a video assistant referee in a competitive game.</p>
<p>Sitting in a van with six TV screens inside the stadium, the assistant quickly proved his effectiveness. He recommended by headset to the on-pitch referee that his initial decision to give Willem II midfielder Anouar Kali a yellow card for kicking an Ajax player’s ankle was too lenient, and Kali was dismissed a few seconds later. </p>
<p>While video refereeing is already routinely used to review decisions in sports like rugby and hockey, football has been late to the party. Ahead of the Ajax-Willem II game it was <a href="http://www.telegraph.co.uk/football/2016/09/02/video-replays-used-for-first-time-during-frances-3-1-friendly-wi/">trialled</a> first in a friendly between Italy and France earlier in September, successfully resolving claims in respect of a yellow card and a penalty. </p>
<p>It was then <a href="http://uk.reuters.com/article/uk-soccer-netherlands-video-idUKKCN11Q0TN">tested again</a> after the Ajax game in Feyenoord’s 4-1 cup victory over FC Oss on September 22, also in the Netherlands. More tests are <a href="http://www.fifa.com/about-fifa/news/y=2016/m=6/news=first-participants-of-video-assistant-referee-experiments-announced-2799518.html">set to follow</a> in different competition formats in Australia, Brazil, Germany, Portugal and United States and there have also been discussions about introducing it in <a href="http://www.dailymail.co.uk/sport/football/article-3607437/Video-technology-aid-referees-FA-Cup-season-replays-used-goals-penalties-red-cards-mistaken-identity.html">England</a> and <a href="http://www.scotsman.com/sport/football/competitions/premiership/scottish-cup-could-trial-video-replays-for-referees-1-4046050">Scotland</a>.</p>
<p>In the system being trialled, the video referee communicates with the referee on the pitch within a few seconds of any incident. As well as advising on penalty and card decisions, they might help clear up cases of mistaken identity or infringements in the lead-up to a goal such as offside or foul play. If the on-pitch referee wishes, they can also review the video footage themselves before making a final decision. </p>
<h2>Goal-line technology</h2>
<p>Video refereeing is a more intrusive extension of goal-line technology, in which video enables football referees to instantly make an accurate call about whether the ball crossed the goal line. Though again arriving much later than in other sports, goal-line technology recently became a feature of top European leagues like the <a href="http://quality.fifa.com/en/News/English-Premier-League-kicked-off-with-goal-line-technology/">English Premier</a>, the <a href="http://www.bundesliga.com/en/news/Bundesliga/Goal-line-technology-to-be-used-in-2015-16.jsp">German Bundesliga</a> and <a href="http://www.espnfc.co.uk/italian-serie-a/story/2297461/serie-a-approves-goal-line-technology-for-next-season">Italy’s Serie A</a>. </p>
<p>It is <a href="http://www.uefa.com/uefaeuropaleague/news/newsid=2365654.html">used</a> at the Champions League and Europe League finals, and was also used at the <a href="http://quality.fifa.com/en/News/GoalControl-confirmed-as-goal-line-technology-provider-for-Brazil-2014/">Brazil World Cup</a> in 2014 and <a href="http://www.dailymail.co.uk/sport/football/article-3632303/Euros-goal-line-technology-used-time-holding-set-pieces-come-close-scrutiny-France.html">Euro 2016</a>. In Germany’s 2-0 group win over Ukraine at Euro 2016, for example, the technology vindicated the referee’s <a href="http://www.dailymail.co.uk/sport/football/article-3638236/Jerome-Boateng-overcomes-injury-doubts-shine-Germany-begin-Euro-2016-campaign-win-against-Ukraine.html">decision</a> to reject goal celebrations by Ukrainian players after a shot was cleared right off the line by German defender Jérôme Boateng.</p>
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<p>International football federation FIFA for a long time <a href="http://bmsi.ru/issueview/d650862e-59a7-4990-86bf-9411ba20d57f/files/apr%202010.pdf">resisted</a> introducing goal-line technology, arguing it would threaten the universality and simplicity of football and the pace of the game, as well as removing some of the controversy and debate between fans. </p>
<p>But the federation came <a href="http://www.fifa.com/about-fifa/news/y=2010/m=10/news=ifab-agrees-examine-goal-line-technology-1320761.html">under pressure</a> to reconsider following <a href="http://www.telegraph.co.uk/sport/football/teams/england/9343883/Euro-2012-Ukraines-ghost-goal-against-England-another-example-of-why-we-need-goal-line-technology-says-Sepp-Blatter.html">numerous</a> high-profile incidents such as Frank Lampard’s disallowed goal for England against Germany at the 2010 World Cup. The technology was finally given the <a href="http://www.fifa.com/mm/document/affederation/administration/01/67/59/87/circularno.1315-furtheramendmentstothelawsofthegame-2012_2013.pdf">green light</a> in 2012. FIFA president, Gianni Infantino, has since also <a href="http://www.bbc.co.uk/sport/football/36085289">spoken positively</a> about it, notwithstanding that the accuracy of the technology <a href="http://pus.sagepub.com/content/early/2008/05/22/0963662508093370.short">is debatable</a>. </p>
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<h2>The fans’ view</h2>
<p>So should football now introduce video refereeing across the board? Not necessarily. Managers and coaches <a href="http://www.bbc.co.uk/sport/football/27726631">tend to be</a> supportive, but fans share many of FIFA’s concerns. The worry is that this is not being taken into account. </p>
<p><a href="http://www.thetimes.co.uk/tto/sport/football/article2528057.ece">Various</a> surveys <a href="https://d25d2506sfb94s.cloudfront.net/cumulus_uploads/document/n8btkavhir/YG-Archive-210612-football-goal-line-technology.pdf">have shown</a> a <a href="http://news.bbc.co.uk/sport1/hi/football/scot_prem/7948765.stm">large</a> majority of fans in favour of video technology, <a href="http://pressreleases.responsesource.com/news/72662/england-fans-support-goal-line-technology-and-the-germans-hattrick/">yet one</a> major international survey from 2012 was much more equivocal. <a href="http://www.thetimes.co.uk/tto/sport/football/article2528057.ece">At least</a> one of the more positive surveys also showed that despite fans’ enthusiasm, they fear it could assume too much importance. “Penalty decisions were the only types of decisions where the majority of fans felt using video refereeing was justified”, it said. </p>
<p>Another <a href="http://footballfanscensus.blogspot.co.uk/2007/05/survey-results-goal-line-technology.html?m=0">earlier survey</a> had 90% of fans fearing that players or managers would use video refereeing to gain a competitive advantage, for example by breaking the flow of the game. Elsewhere, fans <a href="https://d25d2506sfb94s.cloudfront.net/cumulus_uploads/document/n8btkavhir/YG-Archive-210612-football-goal-line-technology.pdf">have fretted</a> that the technology could remove the enjoyment and passion from debating key decisions, particularly when the stakes are high. Both <a href="http://www.tandfonline.com/doi/abs/10.1080/17511321.2012.745896">debating</a> and the <a href="http://search.proquest.com/openview/793ed4aa625cbcc49219185599eeb56e/1?pq-origsite=gscholar">atmosphere</a> at games have been demonstrated through research to be important for spectators’ <a href="http://www.naspspa.org/AcuCustom/Sitename/DAM/067/242_Uhrich_Sport_stadium_a.pdf">experience and satisfaction</a> in football.</p>
<p>At the University of Stirling we found a similar mixture of support and concerns when we <a href="http://hdl.handle.net/1893/23229">surveyed</a> 270 Scottish fans about goal-line technology in 2014. The majority thought the technology detracted from the atmosphere created by contentious goals and lessened the debate around crucial decisions. </p>
<p>They weren’t in favour of in-stadium viewing of goal-line technology, which is <a href="http://www.scotsman.com/sport/football/teams/rangers/cost-of-goal-line-technology-prohibitive-for-scottish-football-1-3995796">currently considered</a> prohibitively expensive by the Scottish Football Association, or of any other video technology being introduced. The more a fan identified with a team, the more strongly they tended to oppose the introduction of future technologies. </p>
<p>All these surveys remind us that the debate around video technology is far from over in football. Seriously damaging the atmosphere at games is arguably not a price worth paying to try and improve the game. It could potentially jeopardise one of the world’s most lucrative commercial products. For that reason, the governing bodies need to proceed cautiously. It is important that football decisions are as accurate as possible, but not at any cost.</p><img src="https://counter.theconversation.com/content/66000/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Mathieu Winand does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>The price of greater accuracy might be to damage fans’ enjoyment.Mathieu Winand, Lecturer in Sport Management, University of StirlingLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/359622015-01-21T19:10:16Z2015-01-21T19:10:16ZBeyond the line call: how Hawk-Eye can improve performance<p>The evolution of professional tennis has always been linked to the changing technology of the day. For example, the decline of the wooden racket lead to the whole new power-based style of play we enjoy today.</p>
<p>One of the more recent introductions to have significant impact is <a href="http://www.hawkeyeinnovations.co.uk/page/sports-officiating/tennis">Hawk-Eye</a> ball tracking.</p>
<p>It’s certainly transformed the way we watch and adjudicate tennis. But can we go further and utilise this truly awesome technology to improve the on-court performance of the competitions elite?</p>
<h2>The traditional use of Hawk-eye</h2>
<p>Hawk-Eye is a computer vision based technology that allows the trajectory of a ball and players to be tracked purely from video. The advantage of such a system is that it’s completely un-intrusive, you don’t need to put sensors in anything.</p>
<p>It’s mostly used to make line-calls, as a back-up when players object to the call made by a lines referee. It’s also used by broadcasters to provide a general overview of a game, set or match.</p>
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<p>Its introduction has seen <a href="https://theconversation.com/a-Hawk-eye-for-detail-how-accurate-is-electronic-judging-in-sport-8136">some debate</a>, but it was nonetheless approved for use at tour level by the International Tennis Federation (ITF) in 2005, after the 2004 US Open Women quarter-final – when Serena Williams lost to Jennifer Capriati – was marred by a series of <a href="http://usatoday30.usatoday.com/sports/tennis/open/2004-09-08-replay_x.htm">dubious line calls.</a>.</p>
<p>In this application, it solves a real problem. It eliminates the human element of line-calling, Hawk-Eye doesn’t feel pressure on big points. It doesn’t come cheap, <a href="http://usatoday30.usatoday.com/sports/tennis/2011-03-09-bnp-paribas-open-hawkeye_N.htm">one report from 2011</a> putting the cost between US$60,000 and US$70,000 per court to operate, <a href="http://uk.reuters.com/article/2015/01/08/tech-israel-tennis-idUKL6N0U20TX20150108">another report this year</a> put that figure at US$100,000 a court.</p>
<p>It’s hard to argue the cost isn’t worth it just for line calls, it would be hard to see us going back to a world where we don’t use ball tracking. But Hawk-Eye isn’t just good for line-calls. </p>
<h2>More to Hawk-Eye than line calls</h2>
<p>Fans only ever really see the brief interaction between ball and court, but Hawk-Eye sees far more.</p>
<p>By collecting data over the entire trajectory of every shot played on Australian show-courts this summer, Tennis Australia (TA) is amassing richer data sources than ever.</p>
<p>At this year’s Australian Open, Hawk-Eye based insights as a tool for pre-match opposition analysis will be greater utilised than ever before by Tennis Australia’s High-Performance unit.</p>
<p>Hawk-Eye has been deployed on multiple courts at the Australian Open and AO series events (Brisbane and Sydney for example) since 2007, and as such we have tracking data for some 250 tennis players.</p>
<p>Thanks partially to funding from an Australian Institute of Sport (<a href="http://www.ausport.gov.au/ais">AIS</a>) grant, an app (like the ones on your favourite smart-phone) has been constructed using <a href="http://www.r-project.org/">open source technologies</a> with Hawk-eye data at its core.</p>
<p>Coaches can log-in from anywhere in the world, and interactivity sort and visualise data, tapping into their unique expertise without the need to consult the performance analysis team every time they want to delve deeper into the data.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/69520/original/image-20150120-24457-1li727y.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/69520/original/image-20150120-24457-1li727y.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/69520/original/image-20150120-24457-1li727y.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=369&fit=crop&dpr=1 600w, https://images.theconversation.com/files/69520/original/image-20150120-24457-1li727y.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=369&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/69520/original/image-20150120-24457-1li727y.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=369&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/69520/original/image-20150120-24457-1li727y.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=464&fit=crop&dpr=1 754w, https://images.theconversation.com/files/69520/original/image-20150120-24457-1li727y.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=464&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/69520/original/image-20150120-24457-1li727y.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=464&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Partial typical output of coaching app. º Spread is standard-deviation.</span>
</figcaption>
</figure>
<p>The above shows part of a typical output for the applet. In this case, only serves hit (from right to left) by Rafael Nadal during tie-breaks are selected. We can see clearly in this case where Rafa’s favourite serve to the deuce side is down the middle, rather than to the side.</p>
<p>The app is essentially a “Google for tennis coaches”, a tie breaker if you will. Ever wondered who hits off-forehands faster, Nadal or Roger Federer? (Nadal by 4kmph) Or who gets a higher net-clearance on serves to the advantage side of the court? (Nadal by half a centimeter), or who hits backhands deeper at 30-40? (Federer by 60cm).</p>
<p>These aren’t debates anymore, and TA coaches can definitively answer questions like these and more at the tap of an app. These insights can be used in a multitude of situations, from planning for a grand-slam opponent to goal-setting for developing athletes.</p>
<p>For example, a coach may suspect a developing athlete is too cautious serving on break point 2nd serves. The coach can use the app, on court from a tablet or phone, to quickly derive typical serve speeds under that exact scenario for a multitude of top players.</p>
<p>Such data quickly eliminates any debate that the hypothetical athlete just doesn’t measure up to the competition, and that they should work on that area of their game.</p>
<h2>Moving beyond ‘stats’</h2>
<p>There’s more to analytics than just stats though, much more. Stats are great but they can often be miss-leading and are almost always misinterpreted. (As Homer Simpson so <a href="https://www.youtube.com/watch?v=PTiBU-1Ji_8">eloquently put it</a>: “You can use facts (stats) to prove anything that’s even remotely true”.)</p>
<p>A growing area of data-science is <a href="http://whatis.techtarget.com/definition/machine-learning">Machine Learning</a>, where you quite literally build simple Artificial Intelligence (AI) algorithms inside computers, which commit large sets of observations to memory and find patterns within, essentially by trial and error.</p>
<p>These algorithms mimic the way we learn, to the extent that one of the most historically successfully algorithms – the artificial neural-network – has structure heavily inspired by that of our own brains.</p>
<p>Machine learning algorithms have been adapted to use Hawk-Eye data in an attempt to uncover trends within matchplay. The result is a “little black book” of potential match-day strategies, which could provide an edge in competition. TA coaches are able to draw on such insights where they see fit as part of the preparation for an opponent.</p>
<p>The system is still very much in development, but has been implemented in some top-level competition. For example, insights derived from data were presented to the player-group prior to Australia’s 2014 Davis cup <a href="http://www.daviscup.com/en/draws-results/tie/details.aspx?tieId=100021096">win over Uzbekistan</a>.</p>
<p>So whether you like it or not, we are heading rapidly into the information age and how we collect and use data is taking over every aspect of our lives.</p>
<p>Sport – and tennis – is no exception.</p>
<hr>
<p><strong>See also:</strong> <a href="https://theconversation.com/a-hawk-eye-for-detail-how-accurate-is-electronic-judging-in-sport-8136">A Hawk-Eye for detail: how accurate is electronic judging in sport?</a></p><img src="https://counter.theconversation.com/content/35962/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Michael Bane received funding from the Australian Institute of Sport Research into Action Fund (2014). Michael Bane's position is co-funded by Tennis Australia</span></em></p>The evolution of professional tennis has always been linked to the changing technology of the day. For example, the decline of the wooden racket lead to the whole new power-based style of play we enjoy…Michael Bane, Research officer, Victoria UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/207412013-12-26T09:58:29Z2013-12-26T09:58:29ZOut! Goal! The ball was in! But could Hawk-Eye get it wrong?<figure><img src="https://images.theconversation.com/files/38390/original/n2yn3c3c-1387797781.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">The eye sees what the camera can't.</span> <span class="attribution"><span class="source">Scot Campbell</span></span></figcaption></figure><p>Hawk-Eye is a device used to reconstruct the track of the ball for LBW decisions in cricket and for line calls in tennis. It will be much in evidence during the remaining Ashes tests and is now being used for goal-line decisions in Premier League football. The technology is at its best when officials make a really bad decision. </p>
<p>But there are things you might not know about Hawk-Eye. For instance, it cannot track the ball to a millimetre even though one might get this impression when watching some replays; in tennis, those shots shown to be touching the line by a hair’s breadth and called in might actually be out and vice-versa.</p>
<p>Few people realised that there was an issue with accuracy until my colleagues and I <a href="http://www.cf.ac.uk/socsi/contactsandpeople/harrycollins/expertise-project/hawk-eye-debate.html">wrote about it in 2008</a>; even top scientists were quite surprised until they thought about it. </p>
<h2>How it works</h2>
<p>Reconstructed track-devices such as Hawk-Eye work by using a number of TV cameras to record the position of the ball in each frame, then a computer reconstructs the path and projects it forward from the last frame. </p>
<p>These devices were first used to aid leg-before-wicket decisions in cricket. The projection-forward principle is the same in tennis since it is unlikely that a camera shutter will be open at the exact moment the ball hits the ground next to the line so the crucial position has to be estimated from a series of previous positions.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/38394/original/7cqjgmb5-1387798891.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/38394/original/7cqjgmb5-1387798891.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=396&fit=crop&dpr=1 600w, https://images.theconversation.com/files/38394/original/7cqjgmb5-1387798891.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=396&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/38394/original/7cqjgmb5-1387798891.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=396&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/38394/original/7cqjgmb5-1387798891.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=498&fit=crop&dpr=1 754w, https://images.theconversation.com/files/38394/original/7cqjgmb5-1387798891.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=498&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/38394/original/7cqjgmb5-1387798891.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=498&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Coming to a football stadium near you.</span>
<span class="attribution"><span class="source">Shuji Kajiyama/AP</span></span>
</figcaption>
</figure>
<h2>What we uncovered</h2>
<p>From the frame-rate of the cameras and the speed of the ball, a back-of-an envelope calculation gave the range of possible accuracy and it turned out to be less than the replays suggested. So we telephoned the firm to talk about it and we hit a wall. As sociologists of science we had spent decades chatting with scientists about this kind of thing but suddenly we were told this information was private and lawyers were on call. Before we could publish our first paper we had to ask Cardiff University to back us in case we were hauled into court.</p>
<p>Our results were based on the range of possibilities for frame-rate and such other technical matters we could glean from the internet but detailed data for these devices was and still is secret. The International Tennis Federation refuses to release the details of its tests and the International Cricket Council also keeps its results under wraps. I have tried and tried to get the information from them and the scientists they commissioned to do the testing but am always met with the claim that the information is commercially sensitive.</p>
<h2>Margins of error</h2>
<p>The problem with reconstructed track devices is that their output is based on estimates. The position of the ball in any one frame is a blob of pixels. The future path of the ball must be extrapolated from at least three frames if the ball is swerving but if it is moving fast and the bounce point is near to the crucial impact point there may not be three frames. </p>
<p>Even with three frames, projections have errors and if, as in tennis, the ball distorts on impact, the footprint on which the line call is based is, again, the result of an inexact calculation – and so on. Hawk-Eye itself used to claim an average error of 3.6 millimetres; more recently it claims this has been improved to average of 2.2mms. However, particularly in tennis, the reliance on this technology to provide a definitive call means that this margin of error isn’t reflected in the replays, leading most fans to assume it is 100% accurate.</p>
<p>Accuracy, of course, will depend on the speed and the angle of the ball and many other factors which is why these are average figures and, as with all averages, on occasion the error will be bigger – sometimes much bigger. To know what is going on one needs details of the tests and the distribution of errors that resulted.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/38395/original/nntjhhzn-1387798945.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/38395/original/nntjhhzn-1387798945.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=381&fit=crop&dpr=1 600w, https://images.theconversation.com/files/38395/original/nntjhhzn-1387798945.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=381&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/38395/original/nntjhhzn-1387798945.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=381&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/38395/original/nntjhhzn-1387798945.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=479&fit=crop&dpr=1 754w, https://images.theconversation.com/files/38395/original/nntjhhzn-1387798945.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=479&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/38395/original/nntjhhzn-1387798945.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=479&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Or is it?</span>
<span class="attribution"><span class="source">Anja Niedringhaus/AP</span></span>
</figcaption>
</figure>
<h2>Tech and circuses</h2>
<p>Assuming that tennis and football lovers, unlike enthusiasts for, say, the professional wrestling circus, want to see fairness as well as an entertaining spectacle, they ought to know more about how the technology is trying to work out what happened to the ball. </p>
<p>When the ball is really close to the line we should see something like a spinning coin to indicate that the final judgement has a lot of chance in it. The crowd would still get its decision and fun but something closer to the truth would be on display. </p>
<p>More and more, computers are able to simulate what looks like reality and this is dangerous for the future of society. The public needs to learn to question technological claims such as those that have been made for anti-missile weapons systems. In certain sports some spectators think that technology is infallible when it is not.</p>
<p>Paul Hawkins, the founder of the Hawk-Eye company, <a href="http://blogs.wsj.com/numbersguy/sports-make-final-call-on-technology-1292/">recently said</a> our arguments were “typical of people who spent a lot of time in universities rather than on the tennis circuit”. He’s right, and thank goodness for that.</p><img src="https://counter.theconversation.com/content/20741/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Harry Collins does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>Hawk-Eye is a device used to reconstruct the track of the ball for LBW decisions in cricket and for line calls in tennis. It will be much in evidence during the remaining Ashes tests and is now being used…Harry Collins, Professor of Social Science, Cardiff UniversityLicensed as Creative Commons – attribution, no derivatives.